Pressure sensing arrays are useful to measure spatial pressure distributions. Some pressure sensing arrays incorporate sensors that measure an external pressure applied to a surface by capacitively relating the applied pressure into an electrical signal. Some capacitive pressure sensors detect pressure applied to an outer conductor by measuring a change in capacitance between the outer conductor and an inner conductor separated by a compliant layer. The compliant non-fluid separation layer compresses due to application of the pressure to the outer conductor causing a change in a separation between the inner conductor and the outer conductor, which in turn changes the capacitance between the inner conductor and the outer conductor.
A different form of capacitive pressure sensor employs a membrane that suspends an outer conductor over an inner conductor, where the outer conductor and the inner conductor are separated by a gap. Semiconductor and/or micro-electromechanical systems (MEMS) processing techniques have been used to make these types of pressure sensors, called “suspended membrane deflection” sensors. Through etching and deposition of materials a conductive membrane can be formed separated from a substrate conductor by a gap. Such sensors detect external pressure by measuring a change in capacitance between the membrane conductor and the substrate conductor caused by changes in a size of the gap, which changes as pressure is applied to the membrane.